Use plantings, paths, steps and retaining walls to make a hillside garden exciting.

Southern California has plenty of hillsides and slopes. Although they can be a challenge to design, they can also become your landscape’s greatest asset. Even if your hillside is not exceptionally steep, water will roll down the hill without sinking in as deeply as it would on flat land. Soil and stones will also roll downhill. The idea of designing a hillside successfully is to keep soil in place while making the area as attractive as possible. Making hills and slopes stable is half of the job. Making them into something beautiful to look at is the fun part. There are many ways to do both at the same time.

Keep soils in place by anchoring the surface with living roots. Choose plants that are drought-tolerant and will grow well with water that may not always seep deeply into the soil. You can plant a low-growing carpet of ground cover plants or you can design in trees, shrubs, bulbs or other plantings to make your hillside exciting. You can even use materials that are not living – like stone, shredded bark (go for the shredded rather than bark chips: they stay in place better), gravel contained with edging materials or patterns of block work, pavers, stepping stones, bricks or other interesting materials.

Another way to handle designing slopes is to terrace them. The concept of terracing is to make the hillside into flat steps that will allow for planting attractive gardens or ground cover. Not only is terracing a good way to stop erosion problems on a hillside, but it turns otherwise non-productive space into something decorative and useful.

To terrace a hillside, you will want to cut out very wide step-like areas. Usually this is done starting at the base. Create the bottom step like a stairway, but carved into your hill. Flatten out the top of a raised area, butting the front against some form of retaining wall. When the soil starts to pile up behind the flat area, build another retaining wall and start flattening out the second tier. This will continue up to the top. Depending on the grade of your slope, the terraced beds can be deep or narrow.

The barrier to keep soil from tumbling forward in the front of each ‘step’ needs to be solid and firm enough to keep the soil behind it in place. A retaining wall can be built of rocks, bricks, cemented blocks, interlocking blocks, railroad ties or many other materials. The more weight behind it, the more stable the structure needs to be. Any wall more than three feet tall will likely require a permit.

Since water washes down with gravity, provisions need to be made for any water that may build up behind the wall structure – especially if you are building solid walls that will fully block the downward flow of water. It’s a good idea to add a drainage pipe and gravel — or at least a buffer zone 10″ thick of gravel behind the back of each retaining wall. This will allow water to drain out from behind the retaining wall rather than press against it.

Hillsides can become areas for vegetable gardens, planted color patterns, or individual garden scenes. Design in effects that will enhance your whole garden. If your garden is formal, consider using a single ground cover type of plant or create symmetrical plantings that can be geometric or controlled. If you want a natural look, blend in natives or sprawling plants in drifts the way nature would. You can also use non-living materials to make a textural statement to fill in between plantings.

Add provisions for maintenance or to get to areas in or behind the hillside itself. This is a perfect opportunity to design in stairways. Stairs can be part of the aesthetic layout of your hillside as well as being a practical passageway. You can lay out steps in straight lines or curve them artistically up the hill. Re-use broken concrete, natural materials or permeable paving to create informal designs. Or pour concrete, carved stone or cast blocks to build a crafted set of steps. Use straight lines or geometric forms to create a contemporary or formal look. You can get as simple or creative as you want when it comes to materials for railings.

If you want to design an artistic feel you can include stepping stones that are painted, sculpted or inlaid. Or you can put together different paving blocks, bricks, cast cement forms, stones, colored gravel or other materials to create your own mosaic design. Another way to create effects is to outline one material with another or fill the flat part of the step with one building material and the rises in another, contrasting material.

You can naturalize your steps by setting large stones or chunks of wood into the ground. Or you could use formal, hewn rock, cast blocks or neatly designed wooden stairs to create other effects or designs. Edges can be hardened with straight borders or softened with plantings.

Landscaping hillsides can actually be an asset to your garden and offer opportunities you’d miss if you didn’t have slopes. So rather than seeing our Southern California canyon slopes as a challenge to the landscape, look at them as opportunities to expand your garden. Hills can be anything but wasted space. Use them for planting orchards, vegetable gardens, seating areas or just make them scenic.

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